In a major breakthrough in the fight against water pollution, a team of materials scientists has developed “engineered living material” capable of transforming toxic industrial dyes into harmless substances. This breakthrough comes at a crucial time, as industrial waste from chemical industries, estimated to be 300 – 400 megatonnes annually, continues to pose a significant threat to our water bodies.

Published in Nature Communications in August 2023, the team’s research showcases the potential of a soft hydrogel material, infused with programmed bacteria, to clean up water pollution. This material, primarily composed of a natural, biodegradable seaweed-based polymer called alginate, serves as a robust support for bacterial cells. This groundbreaking material shares similar properties with Jello and is highly effective due to its porous nature, which allows bacteria to thrive by absorbing nutrients and water from the environment.

The core of this technology lies in the use of photosynthetic cyanobacteria, which are embedded into the alginate hydrogel. These bacteria require light and carbon dioxide to perform photosynthesis and stay alive. To optimize this process, the hydrogel was 3D-printed into custom shapes like grids and honeycombs, significantly enhancing the material’s exposure to light, CO₂, and nutrients. The result? A marked increase in cell growth and density, particularly in these specially designed structures.

But the real magic happens in the transformation of pollutants. The team genetically engineered the cyanobacteria to produce an enzyme called laccase, which breaks down the chemical bonds of pollutants, rendering them nontoxic. This inventive approach was tested with indigo carmine, a common industrial dye and a major pollutant in wastewater from textile industries. Remarkably, this living material managed to remove all color from the dye within ten days.

Ensuring environmental safety, the scientists also engineered a “kill switch” in the bacteria, allowing them to control and destroy the bacterial cells to prevent any additional pollution. This control mechanism responds to theophylline, a harmless chemical found in everyday items like caffeine, tea, and chocolate.

The field of engineered living materials is burgeoning, offering a realm of possibilities for developing new materials that combine living and nonliving components. This discovery not only represents a significant stride in environmental conservation but also opens the door to numerous opportunities in the realm of pollution control. As we continue to confront the challenges of water pollution, this innovative material may prove to be a vital tool in safeguarding our ecosystems and human health. Stay tuned as this exciting field continues to evolve and impact the world.